The requirement for miniaturization of power modules forces power density of the power modules to be increasingly improved. Accordingly, design requirements for heat dissipation are increasing, and many power modules usually have a heat spreader to satisfy the requirement for heat dissipation. Generally, a piece of a metal plate serves as a heat spreader, and fins may be disposed on a side of the metal plate away from a power convertor in the power module, so as to achieve better effect of heat dissipation. Another side of the heat spreader close to the power convertor is a plat surface or comprises several step planes, so as to meet requirements for arrangement of different devices and heat dissipation. Meanwhile, generally a thermal conductive insulating material should be attached onto the side of the heat spreader close to the power convertor, so as to meet requirements for insulation between the conductive devices of the power convertor and heat spreader.
In a heat spreader 91 of the related art, as shown in FIG. 1, one side of the heat spreader away from a power convertor 95, i.e., a lower surface 911 of the heat spreader 91 in FIG. 1, is a flat surface, and fins (not shown) may be disposed on this surface, so as to achieve better effect of heat dissipation. Moreover, another side of the heat spreader close to the power convertor 95, i.e., an upper surface 912 of the heat spreader 91 in FIG. 1, may be a plat surface or comprise several step planes, so as to meet requirements for arrangement of different devices and heat disipation. Meanwhile, generally a thermal conductive insulating material 92 should be attached onto the side close to power convertor 95, so as to meet requirements for insulation between the conductive devices of the power convertor 95 and the metal heat spreader.
Nowadays, there are certain requirements for insulation of the conductive devices on the borders of the heat spreader in the power module, i.e., for a creepage distance between the conductive devices on borders of the power convertor and the heat spreader. However, although the existing design for heat spreader may satisfy different requirements for heat dissipation of power modules, in order to satisfy requirements for insulation of borders of the heat spreader, the layout space for the devices on the printed circuit board has to be reduced, or a volume of the power module has to be increased.
As shown in FIG. 2, in the heat spreader 91 of the related art, the creepage distance between the conductive device 951 in a border of the power convertor 95 and the metal heat spreader 91 is only a sum of a thickness t of the insulating material 92 and a horizontal distance L1 from an end of an upper surface of the thermal conductive insulating material to a right border of the conductive device 951. In order to satisfy requirement for the creepage distance, normally it is required to increase L1, for example, by reducing the printed circuit board or increasing the size of the heat spreader, however, reducing the printed circuit board may result in a reduced layout space for the devices on the printed circuit board, and increasing the size of the heat spreader may result in an increased volume of the power module.
Therefore, a new heat spreader is needed to be developed to solve the technical problems mentioned above.